KINEMATIC CHARACTERISTICS OF IMPACT ABSORPTION DURING LANDINGS OF MULTI-REVOLUTION JUMPS IN FIGURE SKATING

Abstract

Repetitive impact loading is characteristic of the training regimes inherent in the sport of figure skating. Competitive success is largely attributed to the skater's ability to execute multi-revolution jumps, landing backwards, on a single leg, in a prescribed configuration. The primary concern arising as a consequence of repetitive mechanical loading is the potential for impact related injuries. Lockwood & Gervais (1995) quantified impact forces upon landing to evaluate if a potential injury situation exists as a result of this type of training. Results revealed that the magnitude of impact significantly increased with additional revolutions. Two distinctly different landing techniques were identified; soft landings producing less force for a longer period of time and hard landings characteristic of a collision type of contact. The foot-fall timing was significantly shorter for multi-revolution jumps. Since height was not significantly different between jumps, this finding was attributed to increasing rotation during the airborn phase. The purpose of this investigation was to characterize the landing position and the role of kinematic variables on impact absorption. A kinematic analysis of the landing phase of on-ice jumps was performed to examine the possible parameters responsible for the effectiveness of the individual to dissipate impact forces. The magnitude and sequencing of joint segment angles were determined. Athletes were videotape by four cameras at 60 Hz performing single, double, and triple revolution jumps. Standard 3D spatial reconstruction of segmental joint centers was accomplished using the DLT. Data was smoothed using a quintic spline. Results indicated that both knee and hip flexion increased with additional revolutions, however only minimal ankle flexion occured. This was attributed to the stability of the skate providing a mechanical block to increased ankle flexion. Furthermore, the shock wave pattern of flexion from distal to proximal joints which normally occurs as a result of landing, was not evident in on-ice landings. Maximal ankle flexion was preceded by flexion at both the knee and hip joints. Impact absorption appeared to be attenuated primarily by simultaneous knee and hip flexion. Although the human body is subject to the laws of motion, the question that needs to be addressed is whether or not sport technique and equipment respect these laws.